Easing functions specify the rate of change of a parameter over time.
Objects in real life don’t just start and stop instantly, and almost never move at a constant speed. When we open a drawer, we first move it quickly, and slow it down as it comes out. Drop something on the floor, and it will first accelerate downwards, and then bounce back up after hitting the floor.
In the Moovly Studio, the easing function is available for the following animation effects: Fly in/out, Wedge in/out, Wipe in/out, Flow in/out and and Bounce in/out. It can be found in the 'Animation Properties' section, when selecting the object you wish to animate: